Help troubleshooting ignition problem

mark_gober

Petty Officer 3rd Class
Joined
Jan 12, 2009
Messages
76
Hey everyone,

I've got a question regarding troubleshooting my ignition system on my 85 XD18 motor. It's been running rough lately and I rebuilt the carb....still runs rough. I grabbed some high voltage gloves and pulled the lower spark plug wire off and no change in symptoms. Pulled top plug wire off and motor won't run. That tells me that I only have the top cylinder firing. I have a copy of some troubleshooting procedures that Laddies posted in this post...

http://forums.iboats.com/showthread.php?t=303997

My question is this...in the procedure, it lists the DVA output and I'm not sure that I know what this is? At first, I thought it was perhaps a throwback term for a voltmeter. (I've seen references in older manuals for VOM as another word for voltmeter) Now I'm not sure. I used my Fluke multimeter to go to the + terminal of the coil and the black lead to engine ground and I got nothing. The firing cylinder is working because I accidently got across both of the coil terminals with my meter lead and I got a nice spark. (So why do I not read anything on those terminals?)

Laddies makes reference to a direct volt meter in his post. I've been an electronics technician for 13 years and I've never heard that term before. Perhaps someone can make heads/tails out of the procedure for me. I'm mechanically minded and I'm very familiar with internal combustion engines. Laddies also makes reference to high speed windings as well as low speed windings. I'm not sure I know what he means to that also. This is a 2 cylinder engine with two coils and one switchbox. I look forward to hearing everyones thoughts on how to proceed.

Mark
 

86RajunCajun

Petty Officer 1st Class
Joined
Apr 23, 2008
Messages
218
Re: Help troubleshooting ignition problem

The DVA adapter is used with a voltmeter.

It reads Direct Voltage from the stator, power packs etc. With the engine running you would perform the DVA test on the power packs and the stator to make sure they are doing their job giving the coils spark.

You can also test your stator, coils and trigger with a voltmeter by testing resistance in Ohms.

Get yourself a repair manual for your engine and it will direct you on exactly how to test the parts and what to use to do it.

GL!!

RC
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Help troubleshooting ignition problem

Fluke has a DVA Adapter for use with their meters. Used in-line on a AC Volts scale, the adapter adds a measured load to arrive at a peak Volt/Amps measurement.

Many stators contain two (or three) sets of windings of different # of turns and gauge of wire depending on the application of that set.

Low speed ignition, high volts output at low RPM

High speed ignition, high volts output at high RPM

Battery charging, high current, low volts output
 
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